Phenylalanine ammonia lyase (PAL) enzyme activity and antioxidant properties of some cyanobacteria isolates

In the present study, six cyanobacteria isolates were evaluated for the PAL enzyme activity, and their methanol extracts were assessed for the total phenolic amount and other antioxidant parameters. Synechocystis sp. BASO444 and Synechocystis sp. BASO673 isolates with high levels of total phenols (66.0 ± 1.2 μg/mg, 78.1 ± 1.8 μg/mg, respectively) also showed high levels of PAL activities (20.5 ± 3.1 U/mg protein, 17.2 ± 2.3 U/mg protein, respectively) and strong antioxidant activities. To understand the effect of l-phenylalanine (l-phe) on the PAL activity, total phenolic amount, and phenolic constituents, isolates were evaluated with 100 mg/l l-phe. While PAL activities exhibited no significant change with l-phe addition, total phenolic amount of the isolates significantly increased. HPLC analysis revealed gallic acid, trans-cinnamic acid, p-coumaric acid, and ferulic acid as the main compounds. Results suggested that the two isolate mights be an important source for the l-phe inducible phenolic compounds.     

Protective effect of two edible mushrooms against oxidative cell damage and their phenolic composition

The aim of the study was to investigate phenolic composition, antioxidative, protective and cytotoxic effects of Pleurotus eryngii and Auricularia auricula-judae. Analysis of phenolic compounds in these edible mushrooms species has been carried out by high-performance liquid chromatography (HPLC). Protective effect of these mushrooms on H₂O₂ induced oxidative cell damage was determined by using MTT (3-(4,5-Dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole) assay. Antioxidant activities of the mushrooms extracts were evaluated by using complementary in vitro assays. In addition, the measurement of total antioxidant compounds in the extracts was carried out. All the extracts exhibited protective effect against H₂O₂ induced oxidative cell damage but the highest activity was observed for A. auricula-judae aqueous extract (89.5 ± 1.8% cell viability at 0.1 mg/ml). P. eryngii methanolic extract showed the highest ferrous iron chelating ability (IC₅₀ = 0.42 ± 0.03 mg/ml). A. auricula-judae extracts (at concentration of 0.025–0.100 mg/ml) were not toxic to baby hamster kidney fibroblast cell line (BHK 21). These results suggest that these mushrooms may be used as a potential source of natural antioxidants for food supplementation or in the development of nutraceuticals.     

Prevalence and Characterization of Salmonella Isolated from Chicken Meat in Turkey

This study was conducted in a Turkish province to investigate the presence of Salmonella spp. in 150 chicken meat samples using 2 phenotyping techniques: classic culture technique (CCT) and immunomagnetic separation (IMS). For the confirmation of the isolates at molecular levels, invA gene was detected in these isolates. The presence of invA, class 1 (Cls1) integrons, and integrase (Int1) genes was demonstrated by PCR assay; and the resistance of the isolated Salmonella spp. strains to antibiotics was determined by disk diffusion test. All the cultural and PCR results were evaluated together; Salmonella spp. were detected in a total of 64 (42.66%) chicken meat samples. Contamination rate was higher in carcasses (53.33%, n = 75) than in meat pieces (32%, n = 75). When results of standard culture were compared with IMS technique, IMS (n = 54) showed a clear superiority over the CCT (n = 38). A very high resistance rate (≥89.28%) to vancomycin, tetracycline, streptomycin, or nalidixic acid was found. Trimethoprim‐sulfamethoxazole resistance was present in 32.14%. Relatively lower incidence of resistance (≤8.33%) to gentamicin, chloramphenicol, ampicillin, and ceftriaxone was observed. Concurrent resistance to at least 4 antibiotics was detected in 92.85% of the isolates. Cls1 integrons and Int1 were positive in 80.95% and 95.23% of the isolates, respectively. However, Int1 alone was detected in 15.47% (n = 13). In conclusion, the high prevalence of Salmonella spp. in chicken meat may pose a potential public health risk, and the presence of antibiotic‐resistant Salmonella spp. isolate together with Cls1 integron and/or integrase might play an important role in horizontal antibiotic gene transfer.